> ROTARY PISTON ENGINE SYSTEM AND VEHICLE MOUNTED THEREWITH > To provide a rotary piston engine system capable of enhancing intake efficiency, and to provide a vehicle mounted therewith. > SOLUTION: In an engine body 1, there are provided a rotor housing 5 encircling an outer periphery of a rotor, side housings 6 provided on both front and rear sides of the rotor 5, an exhaust port 13 for delivering exhaust gas from a rotor storage chamber 2, and intake ports 11, 12 for introducing intake air into the rotor storage chamber 2. The intake ports 11, 12 are formed in the side housings 6 at a front side so as to open to a lateral face 111 on the front side of the rotor storage chamber 2, and the exhaust port 13 is formed in the side housings 6 on the rear side so as to open to the lateral face 111 at the rear side out of the lateral face 111 in a longitudinal direction of the rotor storage chamber 2. A downstream end of the intake passage 30 extending from the intake ports 11, 12 is arranged at a portion near the upper-part front of the lateral ... > 10 figures